Journal of Polymer Science,
Год журнала:
2025,
Номер
unknown
Опубликована: Фев. 5, 2025
ABSTRACT
Recently,
axial
flexible
substituents
have
found
widespread
application
in
ethylene
(co)polymerization
catalyzed
by
late
transition
metals,
yielding
impressive
results.
In
this
research,
we
designed
and
synthesized
a
novel
class
of
α‐diimine
Ni(II)
Pd(II)
catalysts,
distinguished
their
backbones
that
both
incorporate
cycloalkyl
moieties.
During
nickel‐catalyzed
polymerization,
these
nickel
catalysts
demonstrated
high
activity
(well
above
10
6
g/(mol
Ni·h))
thermal
stability,
producing
polyethylenes
with
very
molecular
weights
(up
to
1022
kg/mol)
branching
densities
103/1000C).
Interestingly,
the
catalyst
reported
study
exhibits
higher
compared
classic
rigid
backbones.
The
resultant
polyethylene
materials
exhibited
outstanding
mechanical
properties
elastic
recovery
(with
strain
(SR)
up
79%),
qualifying
them
as
high‐performance
thermoplastic
elastomers.
contrast,
during
palladium‐catalyzed
palladium
showed
moderate
(level
5
Pd·h))
generated
99/1000C)
203
kg/mol).
case
copolymerization
methyl
acrylate
(MA),
was
notably
reduced
homopolymerization,
resulting
E‐MA
copolymers
lower
densities.
However,
under
experimental
conditions,
successfully
obtained
significant
incorporation
(1.53–4.54
mol%)
MA.
It
is
worth
noting
cyclohexyl
group
displayed
superior
chain
transfer
inhibition
systems
cyclopentyl
group.
Nevertheless,
notable
difference
observed
influence
on
density
regulation:
system,
facilitated
formation
branching,
while
it
had
opposite
effect
when
Polymer Chemistry,
Год журнала:
2024,
Номер
15(14), С. 1437 - 1452
Опубликована: Янв. 1, 2024
In
this
study,
hybrid
steric
hindrance
was
introduced
into
the
α-diimine
structure
to
prepare
a
set
of
nickel
complexes,
aiming
enhance
catalytic
performance
and
polyethylene
properties
simultaneously
for
ethylene
polymerization.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(22), С. 15143 - 15154
Опубликована: Май 23, 2024
Nickel
and
palladium
complexes
bearing
"sandwich"
diimine
ligands
with
perfluorinated
aryl
caps
have
been
synthesized,
characterized,
explored
in
ethylene
polymerization
reactions.
The
X-ray
crystallographic
analysis
of
the
precatalysts
16
6b
shows
differences
from
their
nonfluorinated
analogues
17
19,
centered
precisely
over
nickel
centers,
which
results
higher
buried
volumes
metal
centers
relative
to
analogues.
sandwich
diimine-palladium
5a
5b
containing
polymerize
a
controlled
fashion
activities
that
are
substantially
increased
compared
Migratory
insertion
rates
relevant
methyl
agree
exhibited
bulk
experiments.
DFT
studies
suggest
facility
rotation
its
preferred
orientation
perpendicular
Pd-alkyl
bond
into
parallel
in-plane
conformation
contributes
activity
for
18a.
For
these
systems,
polymer
molecular
weights
can
be
via
hydrogen
addition
(hydrogenolysis),
is
unusual
late-transition-metal-catalyzed
olefin
polymerizations
no
catalyst
deactivation
occurring.
Sandwich
diimine-nickel
6a
show
about
half
those
classical
tetraisopropyl-substituted
2
but
again
more
active
than
analogous
complexes.
Ethylene
exhibit
living
behavior,
branched
ultrahigh-molecular-weight
polyethylenes
(UHMWPEs)
very
low-molecular-weight
distributions
(less
1.1)
obtained.
activated
catalysts
stable
absence
monomer
good
long-term
stability
at
25
°C.
New Journal of Chemistry,
Год журнала:
2024,
Номер
48(27), С. 12174 - 12187
Опубликована: Янв. 1, 2024
A
set
of
five
nonsymmetrical
1,2-bis(arylimino)acenaphthene–nickel
complexes,
incorporating
2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline,
was
designed
and
prepared
to
tailor
the
catalytic
attributes
for
ethylene
polymerization.
Chinese Journal of Chemistry,
Год журнала:
2023,
Номер
41(12), С. 1509 - 1516
Опубликована: Март 2, 2023
Comprehensive
Summary
Usually,
the
aniline‐based
late‐transition‐metal
catalysts
often
require
bulky
steric
substituents
on
both
sides
of
ortho
‐aryl
position
to
achieve
efficient
suppression
chain
transfer
in
ethylene
polymerization.
In
this
contribution,
we
demonstrated
that
α‐diimine
based
naphthylamine
with
only
one
substituent
also
excellent
capabilities
suppress
transfer.
Firstly,
a
class
nickel
and
palladium
complexes
o
‐aryl‐dibenzhydryl
or
‐aryl‐dibenzosuberyl
were
synthesized
characterized.
Secondly,
as‐prepared
naphthylamine‐based
outstanding
activities
(up
13.02
×
10
6
g·mol
–1
·h
)
yielded
lightly
branched
(16—40/1000C)
polyethylenes
very
high
molecular
weights
(445.8—854.3
kg/mol)
comparison,
corresponding
showed
moderate
(level
4
—10
5
),
generating
moderately
(47—78/1000C)
(21.6—82.0
kg/mol).
Moreover,
could
copolymerize
methyl
acrylate
(MA),
albeit
low
3
providing
E‐MA
copolymers
(1.4—16.3
level
incorporation
ratio
(2.4—7.4
mol%)
branching
density
(53—84/1000C).
As
compared
catalysts,
displayed
superior
ability
reactions
give
access
(co)polymers
orders
magnitude
higher
weight
(co)polymerization.
ACS Catalysis,
Год журнала:
2022,
Номер
13(1), С. 725 - 734
Опубликована: Дек. 23, 2022
In
this
study,
several
α-diimine
nickel
complexes
were
prepared
by
merging
a
bulky
dibenzobarrelene
backbone
and
dibenzhydrylanilines.
The
single-crystal
X-ray
diffraction
analysis
confirmed
that
the
complex
Ni1
exists
in
an
anti-conformation,
possessing
quasi-centrosymmetry.
These
displayed
high
activities
(above
106
g
mol–1·h–1)
ethylene
polymerization,
even
at
90
°C,
providing
polyethylenes
with
very
molecular
weights
(well
above
500
kg/mol).
Unexpectedly,
slightly
branched
semi-crystalline
(11-34/1000C)
melting
points
obtained
these
quasi-centrosymmetric
catalysts,
contrary
to
those
common
often
render
highly
polyethylenes.
resultant
have
good
mechanical
properties,
moderate
stress
break
values
strain
values.
Ethylene–methyl
undecenoate
copolymerization
using
also
gave
access
high-molecular-weight
polar
functionalized
copolymers.
experimental
density
functional
theory
calculation
results
suggested
distribution
of
steric
hindrance
as-prepared
complexes,
namely,
catalyst's
structural
symmetry,
might
be
more
favorable
chain
propagation
relative
branch
formation,
which
was
not
observed
polymerization
systems
before.
